1. Field of the Invention
This invention relates to an etching method and apparatus which is utilizable for etching in the manufacture of electronic devices such as semiconductor devices.
2. Description of the Prior Art
Etching techniques have been employed in various fields, in which there is a demand for higher etching rates in order to improve productivity.
For instance, in the field of electronic materials or the production of semiconductor devices, there is a strong demand of increasing the etching rate with an increasing size or diameter of semiconductor wafer and an increasing degree of fineness of pattern. For in-plane uniform etching of a fine pattern in a large-sized wafer, conventional batch systems wherein a number of wafers are treated at one time are not appropriate. An etching process wherein wafers are treated one by one is desirable. However, the treating time in the one-by-one process is only for one wafer with a longer time being required than in the batch system. Accordingly, it is necessary to increase the etching rate so as to increase a treating efficiency.
Some one-by-one etching techniques have been put into practice but cannot be applied to all materials to be treated. For instance, an etching rate for SiO.sub.2 is not so high as to obtain the same throughput as in known batch systems.
For high speed etching, problems involved by the high speed of etching have to be solved.
One of the problems is a damage-preventing problem and another is a problem on uniformity of the treatment.
As for the damage prevention, the etching rate may be increased by using a great etching energy or a highly reactive gas. However, such use has a fear of giving damages on an underlying layer. Although the requirements for high speed etching and reduction of the damage are contrary to each other, both requirements have to be satisfied for realizing the high etching rate.
With respect to the uniformity of the treatment, it may be sacrificed if the energy is increased. For example, if the uniformity is impeded under high rate conditions by adoption of the one-by-one treatment, it will be meaningless to use such a treatment. In Japanese Patent No. 60-11109, there is described a magnetron dry etching method using a high rate treatment with reduced damages. However, there is left a problem on the uniformity. On the other hand, Japanese Patent Publication No. 57-44749 discloses an etching technique wherein uniform treatments are possible with reduced damages. However, a further improvement is desirable with respect to the high speed etching.
Thus, there is a demand for etching techniques which ensure high speed etching and can solve the problems which will be ordinarily involved in the high speed etching, e.g. problems on the damages and the uniformity as discussed above.